scholarly journals Comparative computational analysis of dispersive mixing in extension‐dominated mixers for single‐screw extruders

2020 ◽  
Vol 60 (10) ◽  
pp. 2390-2402
Author(s):  
Vivek Pandey ◽  
João M. Maia
2012 ◽  
Vol 32 (2) ◽  
Author(s):  
Natália Domingues ◽  
António Gaspar-Cunha ◽  
José António Covas

Abstract Models to predict the evolution of the morphology of immiscible liquid-liquid systems and of solid agglomerates dispersion in single-screw extruders were adapted to compute global distributive and dispersive mixing indices. Using these indices, the direct assessment of the mixing ability of a given screw or a comparison of distinct screws becomes readily available. In the case of liquid-liquid systems, the degree of distributive mixing is computed from the extent of deformation of the individual drops, whereas the degree of dispersive mixing is determined by the reduction in drop size. For solid-liquid systems, distributive mixing is quantified by a normalized Shannon entropy, whereas dispersive mixing is defined from the extent of size reduction. The effect of material properties, operating conditions, and geometry of the screw and die is investigated. Finally, the indices are used to determine (via optimization) the operating conditions and the screw geometry that maximize the mixing efficiency.


2006 ◽  
Vol 514-516 ◽  
pp. 1409-1413
Author(s):  
Natália Domingues ◽  
António Gaspar-Cunha ◽  
José A. Covas

Polymer extrusion is one of the most important polymer processing techniques. Modelling of the phenomena developing inside single screw extruders enabled the development of commercial software which can be used to study the performance of existing systems and to define the equipment characteristics for new applications. Although mixing is one of the most important performance measures of extrusion, it is usually disregarded in the available programs. Consequently, in this work mathematical models for quantifying mixing in single screw extruders are developed and subsequently inserted in a global computer modelling program of single screw extrusion. The mixing model quantifies distributive and dispersive mixing and coalescence mechanisms in a liquid-liquid system. This is accomplished by calculating the variation of the thickness of drops considered to be suspended in the polymeric matrix, taking into account the rate and drop break-up time and the coalescence probability. The influence of several parameters, such as viscosities, initial drop dimension, screw speed and barrel temperature, are examined


2006 ◽  
Vol 102 (3) ◽  
pp. 2998-3007 ◽  
Author(s):  
Qu Jinping ◽  
Shi Baoshan ◽  
Feng Yanhong ◽  
He Hezhi

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